Coffee extract and method of making same



April y25, 1939. F4 A. HoUsEMAN l 2,155,971

COFFEE EXTRACT AND METHOD OF MAKING SAME Filed May 5l, 1958 Patented Apr. 25, 1939 4,UNITED sTATEs PATENT OFFICE COFFEE Ex'rRAc'r AND METHOD oF MAK..

me SAME Application May 31, 1938, Serial No. 210,953

17 Claims.

vThis invention relates to new and useful improvements in concentrated aqueous coiee extracts and the method of making such extracts as well as preserving the same against deterioration with age, and is a continuation in part of my copending application Serial No. 155,105, led July 22, 1937.

As is well known the aromatic substances in roasted coiee are essentially responsible for the pleasant aroma of beverage coiee. gredients, commonly grouped under the name caleol, are highly volatile and consequently when a liquid coffee extract is,concentrated by boiling or other form of evaporation at atmospheric pressure or under a vacuum, these desirable ingredients are completely or at least partially lost. This loss of the aromatic constituents of coiiee is naturally most severe in extracts which are evaporated to a dry condition, and is quite substantial even in partially evaporated extracts which Aare thus rendered denitely inferior to beverage coiee when prepared at cup strength by the regularlyaccepted methods in daily use in households, hotels and restaurants.

Various methods have been employed from time to time in an attempt to overcome this aromatic deficiency in coffee extracts and to produce a coee concentrate which when dissolved in hot water will produce a cup of beverage coiee having the desirable aroma, taste and body. One ysuch method consists in trapping or condensing the volatile aromatic constituents which vpass off with the evaporated water and then returning these trapped o r condensed aromatic constituents by one means or another to the concentrate from which they have been evaporated. Another method seeks to reduce the loss of aroma and avor by the addition of glycerine to the extract to be evaporated in order to reduce the vapor pressure of caifeol blanket therefor, further reduction in the loss of aromatic ingredients being sought by evaporating only a portion of the extract and then combining or mixing this evaporated or treated portion with the remainder of the original extract which has not been subjected to evaporation. Neither of these methods is, however, satisfactory since, in each, the extract or at least a substantial portion thereof is subjected to evaporation resulting in a substantial loss of the aromatic ingredients therein.

With the foregoing in mind, the principal object of this invention is to provide a novel method or process of preparing a concentrated aqueous coffee extract wherein the customary evaporation These inby 'acting as a.

of the volatile caieol is eliminated with the result that the loss in aroma and avor aiforded by the ingredients thereof is substantially eliminated.

Another object of the invention is to provide 5 a novel method or process for producing a concentrated aqueous colee extract of the character set forth which includes certain novel steps for preserving the coiee extract against deteriora,- tion and loss of the aromatic ingredients therein. 10'

More particularly the invention contemplates the production of a concentrated aqueous coffee extract containing the aromatic ingredients essential to good beverage coiee and then freezing said extract into solid form for the purpose of 15 preserving the same against deterioration and loss of said aromatic constituents due to hydrolysis, oxidation or other forms of decomposition.

These'and other objects and features of the invention are set forth in detail hereinafter and 20 shown in the accompanying drawing in which Figure 1 is a diagrammatic illustration of one form of apparatus that may be successfully used to carry out the method or process contemplated by this invention. 25

During the course of experiments relating to coffee extracts, I observed that when water alone at a temperature of from F. to 212 F. was allowed to percolate through a relatively long column of ground roasted coffee, a concentrated percolate resulted which, when diluted with hot water to brew a cup of coee, did not impart to that beverage the full rich avor, aroma and body required by the accepted standards for a good cup of coffee because, while the Water furnished the necessary solvent action for the water-soluble solids of the coffee, the volatile aromatic constituents thereof were not driven off, with the result that the coffee was somewhatat and decient in the proper proportion of aroma and bitterness. On the other hand, I also observed that when steam alone is caused topass through a similar column of ground roasted coffee, while' the aromatic constituents thereof are driven oi, the steam does not furnish the necessary solvent action for the water-soluble solids of the coffee bean.

moved together from the cylinder, provide an extract so blended as to contain all of the desirable constituents necessary to a coee concentrate which when diluted with hot water to make a cup of coffee produces a beverage of fine and true flavor having full body and aroma.

Referring now to the drawing, one form of apparatus which may be employed to carry out my invention comprises a plurality of vertically arranged extracting columns or cells designated I, 2, 3 and 4 respectively, and preferably insulated and constructed of heat resistant glass, or other material resistant to corrosion by the coffee extract. The upper and lower ends of each cell are normally closed by means of suitable caps or cover elements 5 and 6 respectively provided with a suitable number of openings therethrough to receive one or more tubes or pipes and permit charging and `discharging of said cells. As shown a pipe 'I having a control valve or the like 8 therein extends into the top of the cell I through an opening in the cap 5 and has its other end connecting with a hot water supply line 9. In a similar manner, pipes 1a, Ib and 'Ic lead respectively from the main water line 9 into the upper ends of cells 2, 3 and 4, and these pipes as in the case of pipe 'I are provided with valves 8a, 8b and 8c, respectively, for controlling the flow of hot water from the said line 9 to the several cells 2, 3 and 4.

Also extending into the upper end of the cell I through another opening in the cap or cover 5 is a pipe I which leads from a main steam line II and is provided with a valve or the like I2 therein for controlling the flow of steam from said line II to the cell I. In similar manner pipes Illa, IIlb and lIl'I'c lead respectively from the main steam line II into the upper ends of the cells 2, 3 and 4 and these pipes, as in the case of the pipe I0, are provided with valves I2a, I 2b and I2c respectively for controlling the iow of steam from the said line 'I I to the several cells 2, 3 and 4.

Extending into the lower end of the cell I through an opening in its closure '6 is an outlet pipe I3 which leads through a T section I4, valve I5, rotary pump I6 and upwardly through a second valve I'I from which it connects into the hot water pipeline Ia below the valve 8a located therein, said pump I6, as well as pumps I6a, IGb

and IIic hereinafter mentioned, being of such designed capacity as will take care of the volume of liquid extracted from each cell including water and condensed steam. `In similar manner, each of the cells 2 and 3 are provided with pipes I3a and I3b respectively which lead from the lower end of such cell through T sections -I4a and Hb, valves I5a and I5b, rotary pumps IIia and ISb and upwardly through other valves IIa and I1b into the pipe lines `Ib and Iclleading into the upper end of the next succeeding cell 3 or 4 as the case may be, and a pipe I3c having suitable control valves I 5c and I'Ic therein, as well as a rotary pump I6c leading from the lower end of the cell 4 through a T section I4c back to the fresh water feed line I leading from the main 9 into the upper end of the cell I. For the purpose'of permittlngthe apparatus to be tapped after or at each stage thereof, each of the T sections has its downwardly extending branch connected through suitable taps or valves I8, I8a, I8b and I8c to an exhaust pipe or nipple I9, Isa, I9b and I9c respectively.

In carrying out the method of my invention, suitable quantities of freshly roasted, ground cofn fee are placed in each of the cells I, 2, 3 and 4 and these columns of coffee are supported at their lower end in spaced relation to the outlet pipes I3, I3a, I3b and I3c by means of suitable perforated plates or screens 28 of such construction that the ground coffee will not pass therethrough although liquid will be permitted to do so. Steam at a suitable pressure is then allowed to pass into the top of the cell I from the steam line I I through the 'pipe I0 and when the steam has passed a predetermined distance down the column of coffee therein, hot water-at a suitable temperature is similarly admitted tok the top of the cell I throughpipe 1, the flow of steam and hot.water being controlled by the valves I2 and 8 in conjunction with suitable metering devices such asV of iow of each may be regulated to further con- O trol thev temperature and density of the coffee extract collected at the bottom or lower end of the cell I below the column of coffee therein.

The distillate and solution fractions thus produced collect and combine during passage through the column of coffee Within the cell I and the re-I sulting extract passes out of said cell I through the outlet pipe I3 from which it is withdrawn through the tap I8 therein so long as its density does not fall below a given density. When, however, the density of the extract does fall below such given density, the tap I8 is closed so that the remainder of the extract which is of lighter density will be pumped through the pipe I3 and be admitted into the top of the second cell 2 through pipe 'Ia either alone or together with fresh Water from the main 9, control being effected by means of the valve 8a in said pipe 1a.

- However, prior to admission of this hot Water and/ or lighter density extract to the cell 2,y steam is admitted into the top thereof from the line II through the pipe or tube Illa so that the said steam may pass a predetermined distance down the column of coffee in the cell 2 before water and/or lighter density extract are admitted thereto. f

As previously described in connection with the cell I, the extract produced is collected at the lower end of the cell 2 after which it is drawn off from the outlet pipe I3a `through the tap I8a until the density of the extract falls below that desired at which time said tap I 8a is closed and the remainder of the extract which is of lighter density is pumped through said outlet pipe I3a into the upper end ofthe cell 3 wherein the processes and steps described in conjunction with cells I and 2 are repeated, the low density portion of the extract,'after withdrawal through the tap I8b of that portion having a density not less than that desired, being pumped into the top of cell 4 in which thev stepsl previously described in conjunctionwith cells I, 2 and 3 are again repeated except that the lighter density extract, after withdrawal through the tap I8e of extract having a given density or greater, mayor may not be returned throughthe outlet pipe I3c back into the fresh feed water line 1 for recirculation in one or more stages of the apparatus after the. cells have -been recharged with a fresh supply of freshly roasted, ground coiee of good quality. In this manner continuously and when it is necessary to recharge any one cell with ground roasted coiee such cell may be shut off from the remaining cells by appropriate manipulation of the several valves I5, 15a, I5b or |50 and I1,\I1a, Ilb or I'lc as the case may be, thus permitting extraction to continue uninterrupted in the remaining cells.

By way of more specifically illustrating the control and regulation of the steam and' hot water admitted to the several cells as regards the respective rates of flow of each, the pressure of the former and the temperature of the latter, I have found that generally satisfactory results are obtained, in the case four pounds of freshly roasted, ground coffee are placed in cells three inches in internal diameter and sixty inches high, when steam is admitted at a uniformly controlled pressure of approximately three pounds gauge and at a rate of flow regulated to approximately 0.12 ounce per minute. 'I'he hot water on the other hand is admitted to each cell at aregulated rate of ow of approximately 5.0 ounces per minute and at a uniformly controlled temperature of 200 F., said hot water being admitted tothe cells when the initially admitted steam has travelled substantially two-thirds of the way down the columns of colee therein so that the hot water and steam extracts will arrive at the bottom or lower end of said columns of coffee at approximately the same time. The extract collecting at the lower end of the cells below the columns of coffee therein has a temperature of approximately 200 F. and the extract thus prcduced during the first portion of the treatment has a density of 16 Twaddell or greater (measured at 70 F.) which is generally the density desired, and is removed through valves I8, I8a, |8b and I8c, respectively. Extracts of lower density are usually pumped to the top of the next succeeding still.

The temperature at which the fresh feed water is admitted. to the several cells as well as the pressure of the steam admitted thereto, may, of course, vary widely and a satisfactory extract is generally obtained by employingwater at temperatures of from 100 F. to 212 F., and steam at from one pound to twentypounds gauge pressure in suitable proportions and under such control as respects rate of ilow and admission to give the resulting extract a predetermined temperature and Twaddell density. Other than the specific example given in the preceding paragraph, these variables vcannot be definitely xed or correlated with respect to one another except by test and experimentation based upon conditions employed and density desired in the extract to be produced. 'I'he temperature within the several cells may be further controlled to secure the proper equilibrium between the distillation and extraction `phases by providing said cells with externally arranged heated jackets or any other means capable of controlling the temperature interiorly thereof.

In some instances, depending upon various factors and particularly the blend and degree of roasting of the coffee employed in making the extract, I have found that the initial portion of the extract produced has a decided objectionable odor and a sour or acid taste which is imparted to said extract by the volatile constituents in the coffee initially distilled ofl by the steam which is passed oi therethrough and in such cases I may eliminate such objectionable odor and taste vfrom the extract by controlling the times of admission and rates of ow of steam.and hot water through the columns of ground roasted coffee so that the steam arrives at the lower end or bottom of such column slightly ahead of the hot water, thus permitting withdrawal and discard or rejection of the initial portion of the steam distillate before the true extract consisting of the combined steam distilled volatile constituents and water soluble solids arrives at the outlet .the column of ground coffee or concentrated in the form of a layer at the' bottom thereof, and while the percentage of calcium carbonate required in a given case may vary widely, percent-` ages from 0.1% to 5.0% calculated on the weight of the ground roasted coffee bean generally afford satisfactory adjustment and control of the acidity of the extract. In lieu of employing either one of the procedures mentioned for eliminating objectionable odor and taste in the extract, it will be obvious, of course, that they may be employed simultaneously and in conjunction with one another.

In order to preserve the coffee extract thus -produced against-deterioration with age and loss of the aromatic constituents therein which re sult from the action of hydrolysis, oxidation or other decomposition, said concentrated extract is preferably frozen solid immediately or as soon as possible after it is withdrawn from the several cells through the taps I8, Isa, I8b and I 8c preferably to a cooling tank or chamber (not shown). 'I'he freezing point of the liquid extract or concentrate is somewhat below 32 F. Superior resultsfhowever, generally are obtained when a temperature of F. or lower is employed and the frozen product is maintained and stored at or near this temperature until delivered to the ultimate consumer. Any well known refrigerant or system of refrigeration may be employed to freeze the liquid extract, and for example, a satisfactory product may be produced by freezingl appreciable hydrolysis, oxidation or other decomposition occurs.

While the illustrated form of apparatus for carrying out the present invention contains four stages or cells, it is pointed out and should be obvious that the said invention may be effectivelyl practiced by employing a single or any other number of cells, but for economy and continuity of operation, it is preferred that a plurality of such stages or cells be employed. Furthermore, while a specific example of the invention has been herein'set forth for descriptive purposes, it is not Vintended that said invention be precisely limited thereto but that changes, variations and modifications may be incorporated and embodied herein within the scope of the annexed claims.

I claim:

1. The method of making 'concentrated aqueous coffee extract which comprises subjecting the ground roasted coffee to the combined action of steam to distill the aromatic ingredients therefrom and of--hot water water-to effect a solution of the water-soluble solids therein, combining the condensed distillate and said solution and thereafter removing the combined extract from the ground coffee.

2. The method as claimed in claim 1 wherein calcium carbonate is associated with the ground roasted coffee for the purpose of adjusting the pH of the extract produced.

3. The method of making concentrated aqueous coffee extract which comprises passing steam and hot water downwardly through an enclosed column of ground roasted coffee to distill the aromatic ingredients therefrom and to effecta solution of the water-soluble solids therein, and collecting the combined extraction products at the lower end of said column of coffee.

4. The method as claimed in claim 3 wherein calcium carbonate is associated with the ground roasted coffee for the,purpose of adjusting the pH of the extract produced.

5. The method as claimed in claim 3 wherein a layer or thickness of calcium carbonate is provided at the lower end of the column of coffee for the purpose of adjusting the pH of the extract produced, the percentage of said calcium carbonate being not in excess of 5% by weight of the coffee.

6. The method of making concentrated aqueous coffee extract which comprises passing steam and hot Water downwardly through an enclosed column of ground roasted coffee to distill the aromatic ingredients therefrom and to effect a solution of the water-soluble solids therein, collecting the combined extraction products at the lower 'end of said column of coffee, and respectively regulating the pressure and temperature of said steam and water during passage thereof through the coffee to control the temperature and density of the extract produced by such combination of said distillate and solution fractions.

'7. The method as claimed in claim 6 wherein calcium carbonate is associated with the ground roasted coffee for the purpose of adjusting the pH of the extract produced.

8. The method as claimed in claim 6v wherein a layer or thickness of calcium carbonate is provided at the lower end of the column of coffee for the purpose of adjusting the pH of the extract produced, the percentage of said calcium carbonate being not in excess of 5% by weight of the coffee. v

9. The method of making concentrated aqueous coffee extract which comprises passing steam and hot water downwardly through an enclosed column of ground roasted coffee to distill the aromatic ingredients therefrom and to effect a solution of the water-soluble solids therein, controlling the relative proportions and rates of flow of said steam and hot water so that the same initially reach the lower end of the column of coffee at substantially the same time, collecting the combined extraction products at the lower end of said column of coffee, and respectively regulating the pressure and temperature of the steam and water during passage thereof through the coffee to control the temperature and density ofthe extract produced by such combination of said distillate and solution fractions.

10. The method of making concentrated aqueous coffee extract which comprises passing steam and hot water downwardly through an enclosed column of ground roasted coffee to distill the aromatic ingredients therefrom and to effect a solution of the water-soluble solids therein, co1- lecting the combined extraction products at the lower end of said column of coffee, respectively regulating the pressure and temperature of said steam and water during-passage thereof through the coffee to controlthetemperature and density of the extract produced by such' combination of said distillate and solution fractions, withdrawing so much of said extract as has not, less than a predetermined density, and passing the remainder of said extract downwardly througl'i'a second enclosed column of ground coffee together with hot water and steam to produce an additionall quantity of extract by the distillation of the aromatic ingredients and solution of the water-soluble solids therein as described.

11. The method of making concentrated aqueous coffee extract which consists in passing steam and hot water downwardly through a plurality of enclosed columns of ground roasted coffee for the purpose of distilling off'the aromatic ingredients and effecting a solution of thewater-soluble solids therein, collecting the combined extraction products at the lower end of each of said columns of coffee, respectively regulating the pressure and temperature of said steam and water during passage thereof through the several columns of coffee to control the temperature and density of the extract produced by such combination of said distillate and solution fractions, withdrawing so much of the extract collected below each column of coffee as has not less than a predetermined density, and passing the remainder of said extract downwardly through another of said columns of ycoffee together with steam and hot water to form an extract therefrom.

12. The method of making concentrated aqueous coffee extract which comprises passing steam and hot water downwardly through an enclosed column of ground roasted coffee to distill the aromatic ingredients therefrom and to effect a solution of the water-soluble solids therein, controlling the relative proportions and rates of flow of said steam and hot water so that steam reaches the lower end of the column of coffee in advance of the hot water to initially distill off certain objectionable ingredients in the coffee, discarding said initial steam distillate, and thereafter collecting the combined succeeding steam distillate and the water soluble solids at the lower end of said column of* coffee.

13. The method of making concentrated aqueous coffee extract which comprises passing steam and hot water downwardly through anenclosed column of ground roasted coffee to distill the aromatic ingredients therefrom and to effect a. solution of the water-soluble solids therein, controlling the relative proportions and rates of flow of said steam and hot Water so that steam reaches the lower end of the columnof coffee in advance of the hot water to initially distill off certain objectionable ingredients in the coffee, discarding said initial steam distillate, and thereafter collecting the combined succeeding steam distillate and the water soluble solids at the lower end of said column of coffee, and respectively regulating the pressure and temperature of the steam and water during passage thereof through the coffee to control the temperature and density of the extract produced by such combination of said distillate and solution fractions. f

14. The method as claimed in claim 12 wheresol in calcium carbonate is associated with the ground yroasted coffee to aid in correcting the acidity of the extract produced.

15. The method of making concentrated aqueous coiee extract which comprises passing steam and hot water downwardly through an enclosed column of ground roasted coffee to distill the aromatic ingredients therefrom and to elect a solution of the water-soluble solids therein, controlling the relative proportions and rates of flow of said steam and hot Water so that steam reaches the lower end of the column of coiee in advance of the hot water to initially distill oi certain objectionable ingredients in the coffee, discarding said' initial steam distillate, and thereafter collecting the combined succeeding steam distillate and the water soluble solids at the lower end of said column of coffee, withdrawing so much of the extract produced as has not less than a predetermined density, and passing the remainder of said extract downwardly through a second enclosed column of ground coiee together with hot water and steam' to produce an additional quantity of extract by the distillation of the aromatic ingredients and solution of the watersoluble solids therein as described.

16. 'I'he method of making concentrated aqueous coiee extract which comprises passing steam and hot water downwardly through an enclosed column of ground roasted coiee to distill the aromatic ingredients therefrom and to eiect a solution of the water-soluble solids therein, controlling the relative proportions and rates of-flow of said steam and hot water so that steam reaches the lower end of the column of coffee in advance of the hot water to initially distill ol certain objectionable ingredients in the coffee, discarding said initial steam distillate, collecting the combined succeeding steam distillate and the water soluble solids at the -lower end of said column of coee, withdrawing so much of the extract produced as has not less than a predetermined density, passing the remainder of said extract downwardly through a second enclosed column of ground colee together with hot water and steam to produce an'additional quantity of extract by the distillation of the aromatic ingredients and solution of the water-soluble solids therein as described, and controlling the relative proportions and rates of flow of said steam and hot water so that the former reaches the lower end of the column of coffee in advance of the hot water to initially distill off certain objectionable ingredients in said colee.

17. The method as claimed in claim wherein calcium carbonate is associated with the ground roasted coffee to aid in correcting the acidity of the extract produced.

PERCY A. HOUSEMAN. 

